The invention is directed to a novel device and method of providing cardiac compression during cardio-pulmonary resuscitation (CPR) to provide the necessary cardiac output for adequate circulatory perfusion by simultaneously inflating the patient""s lungs and inflating an esophageal balloon orally inserted to a position posterior the patient""s heart, and including an automatic ventilator for simultaneous lung and balloon inflation.
Cardio-pulmonary resuscitation involves the compression of the patient""s heart by application of pressure squeezing the chambers of the heart in order to maintain at least a minimal degree of blood circulation after the patient suffers a heart attack or other condition which causes the heart to cease pumping.
A conventional CPR method involves vigorously applying external pressure with the practitioner""s hands to the patient""s chest. A significant level of skill is required to provide consistently timed compressions of sufficient strength to compress the heart and result in adequate perfusion. This method has the advantage that a trained person can apply CPR rapidly without external equipment. However, the retention of the skill has been shown to be somewhat limited over time if the practitioner does not have an opportunity to practice often. There are significant dangers inherent in this method such as the risk of fractured ribs, internal bruising or other complications. These disadvantages are recognized in the medical literature such as for example in Krischer Fine. Davis and Nagel: xe2x80x9cComplications of Cardiac Resuscitationxe2x80x9d Chest 1987; 92:287-291.
A second commonly used method of cardio-pulmonary resuscitation is the direct squeezing of the heart in an internal cardiac massage. Although this method provides improved blood perfusion, compared to the above described externally applied CPR method, obviously open chest heart massage is simply not feasible in rescue or ambulance field conditions due to the need for surgical intervention. Direct heart massage therefore is limited to use as a last resort in an emergency within hospital conditions. Due to the major surgical intervention required, open chest heart massage is of extremely limited application.
The most commonly used method of CPR where external pressure is applied on the chest has been analyzed in clinical studies and is reported to generate cardiac output by compression of the heart between the posterior aspect sternum and the interior aspect of the vertebral body. The external pressure on the chest flexes the sternum and ribs toward the spine and collapses the esophagus between the posterior aspect of the heart and the spine. For example, see: Kouwnehove, W. B; Jude, J. R: Knickerbocker G. G: xe2x80x9cClosed chest cardiac massagexe2x80x9d. J.A.M.A. 173: 1064, 1960.
Further research has put forward the conclusion that conventionally applied external cardio-pulmonary resuscitation does not generate blood flow through actual heart compression but rather increases intrathoracic pressure which generates blood flow. To date both theories remain controversial, namely whether the heart is actually compressed, or the external pressure increases intrathoracic pressure that generates blood flow independent of the heart. Further research has pursued the concept that a combination of increased intrathoracic pressure together with heart compression can be used to generate increased blood flow during CPR. Such research has been done using synchronous ventilation and externally applied cardiac compression theoretically combining these theories however with mixed results. See for example: Swenson, R. D; Weaver, W. D: Naskanen R. A., Martin. J: Dahlberg, S: xe2x80x9cHemodynamics in humans during conventional and experimental method of cardio-pulmonary resuscitationxe2x80x9d, Circulation 1998; 78:630-639; and Chandra. N: Rudikoff, M; Weisfeldt. M. L: xe2x80x9cSimultaneous chest compression and ventilation at high airway pressure during CPRxe2x80x9d Lancet 1980; 1:175-178.
Further clinical research has shown that cardiac output can be achieved by applying external pressure to the heart during lung inflation. See: Beyar R: Kishon Y: Kimmel, E: Neufeld H: Dinnar U: xe2x80x9cIntrathoracic and abdominal pressure variations as an efficient method for CPR: studies in dogs compared with a computer modelxe2x80x9d. Cardiovascular Resuscitation 1985; 19,6: 335-42; Beyar R: Kishon, Y: Neufeld, H: Dinnar, U: xe2x80x9cCPR by intrathoracic pressure variations-in-vivo studies and computer simulationxe2x80x9d. Angiology 1984; 35, 2: 71-78; and Robotham, J. L.: xe2x80x9cCardiovascular disturbances in chronic respiratory insufficiencyxe2x80x9d. American Journal of Cardiology 1981; 47,4:941-949.
It is an object of the invention to combine the positive aspects of the above theories and existing methods of CPR in a novel method which produces cardiac output and blood circulation during CPR in a manner with consistent results, provides improved blood perfusion, can be applied in a simple manner and is minimally invasive.
It is a further object of the invention to provide a new method of CPR with application that provides predictable consistent results independent of the particular skills of the CPR practitioner and independent of the physical characteristics of the patient.
It is a further object of the invention to provide a novel method of CPR that can be operated automatically thereby freeing paramedics to perform other necessary medical functions. In contrast, conventional CPR methods require the fall attention and both hands of the CPR practitioner.
It is a further object of the invention to provide an easily used, low cost device, which ideally includes disposable components to minimize the risk of cross-infection, and includes an automatic patient ventilation device which can be independently used for ventilation when heart operation recommences, or in other paramedic operations where cardiac arrest is not diagnosed.
Further objects of the invention will be apparent from review of the disclosure and description of the invention below.
The invention relates to a device for and method of cardio-pulmonary resuscitation (CPR) involving cardiac compression of a patient""s heart through expansion of the esophagus with an orally inserted balloon.
Traditional CPR applies external pressure to the patient""s chest at the sternum in an attempt to compress the heart thereby forcing blood flow through the heart. This prior art CPR method is often ineffective or highly inefficient since the applied external force is dissipated as the force deflates the lungs, flattens the chest cavity and collapses the esophagus posterior the heart.
The method of the invention expands the esophagus with a cyclically inflated and deflated balloon in the local area between the heart and the spine to exert a more effective local compression to the posterior of the heart. Preferably the lungs are inflated simultaneously to contain and further compress the heart during local esophageal compression.
Specifically, the method includes orally inserting an elongate esophageal insert having a distal tip and a proximal end to an inserted position where the tip is disposed within the esophagus posterior the heart. The insert includes an esophageal expansion balloon located on the tip for inflating and deflating the esophagus when supplied with tidal volumes of pressurized gas from an automatic cycling ventilator. The ventilator preferably is also fitted with an orally inserted tracheal tube with inflatable tracheal sealing cuff to simultaneously inflate the patient""s lungs with tidal volumes of pressurized gas.
Further details of the invention and its advantages will be apparent from the detailed description and drawings included below.